1. Field of the Invention
The present invention relates generally to methods and apparatus for minimizing the moisture in a carboxylic acid product wet cake. More specifically, the present invention concerns methods and equipment suitable to produce a carboxylic acid particulate product wet cake comprising less than about 12 weight percent moisture.
2. Description of the Prior Art
In conventional crude terephthalic acid (CTA) production processes, para-xylene undergoes oxidation to form CTA particles. The CTA particles are then typically subjected to isolation and washing. In a conventional purified terephthalic acid (PTA) production process, an additional step is employed where the CTA is purified prior to the isolation/washing step. In either a CTA or a PTA production process, the terephthalic acid (TPA) particles exiting the isolation/washing step are typically in the form of a wet cake. In some TPA production processes, the wet cake is then dried in a dryer to thereby produce a dried TPA product.
Various techniques are known in the art for isolating TPA particles from a slurry. An example of one such technique includes the use of a vacuum filter. Vacuum filters typically employ a filter cloth through which the liquid phase of the slurry is drawn using a vacuum source, thus leaving a filter cake of TPA particles on the cloth. However, conventional techniques for isolating TPA can be problematic due to the fact that product wet cakes produced using these techniques typically have a relatively high moisture content. A TPA product wet cake having a high moisture content will require more extensive drying to be suitable for sale or use in subsequent processes, thus increasing overall production costs. Accordingly, there is a need in the industry for methods and apparatus that are capable of reducing the moisture content of an isolated TPA product wet cake.